Over the past several years, a substantial number of automatic speed controls or cruise controls for automotive vehicles have been developed. Depending on the mode of actuation, many of these systems are extremely complex and involve highly sophisticated electronic or mechanical constructions. As an example, one version of an electronic speed control utilizes an electronic memory with almost instantanous speed memorization and single wire transmission of control signals from the steering wheel to a computer as a vehicle-velocity control device. Such a device involves complex circuitry to provide the operations of sensing the speed of the vehicle, a low speed cutout, memory and comparitor, a driver amplifier, a throttle feedback circuit, and brake disabling circuits.
Other types of speed control devices may incorporate magnetic speed sensing means, fluid pressure modulators, and intake manifold air pressure or vacuum means. However, many of such prior devices required expensive proportioning valves and solenoids for proportioning and metering the flow of actuating fluids within the speed controlling system, and the complexity and cost of such systems has made them prohibitive for general application to vehicles and virtually impossible for addition to vehicles once the vehicles were manufactured and sold by the original vehicle builder.